Autofocus Lens Mimics the Eye

Photonics.comOct 2011
TRONDHEIM, Norway, Oct. 14, 2011 — Making cell phone cameras work more like the human eye may help overcome limitations in low light sensitivity and focusing.

Most cell phones today have built-in cameras, but these are not equipped with autofocus capabilities, as are ordinary photographic cameras. The small aperture of the cameras’ lenses results in an acceptable depth of focus, but also admits limited amounts of light, making indoor photography difficult and the photos often not very sharp.

Dag Wang and his colleagues at Sintef have created an autofocus lens that mimics the human eye. (Photo: Geir Mogen)
Several years ago, a group of scientists affiliated with the Scandinavian research organization Sintef began exploring ideas for new energy-saving features that would provide autofocus in small optical systems.

An important requirement was the ability to focus the lens sharply, which is normally achieved by moving lenses. But this requires energy, and the optimal solution would therefore be to change the curvature of the lens itself, just like the lens of the human eye.

What the Sintef researchers needed, therefore, was some sort of soft and variable lens and a material that could mimic the eye muscles that control the lens.

“The idea of creating an autofocus lens using the principles found in nature got us thinking at the time,” Dag Wang said. “The result was a sketch of an optical ‘sandwich’ consisting of extremely thin glass plates, a polymer, a gel material and a metal alloy with flexible properties — all at very small scale.”

The required material was developed to order. To succeed, the researchers had to make a ring of material contract and expand almost without expending energy — and at the same time construct a gel-based lens in the middle.

Earlier this year the company demonstrated the new camera lens, integrated into a mobile phone camera, to interested specialists at Mobile World Congress in Barcelona, Spain. Now, Apple Inc. and Nokia Corp. are among the companies interested in introducing it.